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  1. Ng2020

    Steel Sleeve Around Bearing

    You eould not typically need a plain bushing to install a bearing into an aluminium fitting. (Unless it's a swage sleeve? )
  2. Ng2020

    Re-framed- Skin shear flow with ribs

    Shear flow is constant in all bays. As others mentioned, the purpose of a wing box rib is manifold - It provides a means to maintain wing aero profile under load, it prevents upper skin collapsing onto lower skin as the wing bends, conducts skin out of plane pressure loads into spars, it...
  3. Ng2020

    Lilium down the gurgler

    Analogous to Reason's swiss cheese model: for a project to be truly successful - from concept through first flight through to production and market acceptance- there are many holes in the swiss cheese which require concentricity. I am doubtful of the technical integrity of most urban air...
  4. Ng2020

    static loads and 3Sigma Loads

    To me it sounds like the 3 sigma psd load is intended as an equivalent static criteria load. Sometimes this is done to simplify design/abalysis in applications where vibration dominates, rather than the flight/ground static loads. If that's the case here then it's probably not appropriate to...
  5. Ng2020

    Failure of Wind Fence due to corrosion

    Some guesses as to the mechanisms at play: Salt spray accumulates on the polyster mesh, then concentrated salt solution wicks into the joint when it rains. Regarding the mesh failure: corrosion products/salt crystals between the mesh and lockbar might be abrading the polyester under wind...
  6. Ng2020

    Crippling stress - Plasticity factor

    Crippling is, by definition, an entirely plastic failure mode. Therefore there is no additional plasticity correction factor as you might use when developing buckling critical stresses (which is an elastic mode for thinner elements, and involves plastic deformation for thicker elements)
  7. Ng2020

    Parallel hybrid EV with direct torque coupling - torque ratings of components

    Consider the freebody of the driveshaft, elec motor & wheels - 1000nm is applied to the system at the transmission output end of the driveshaft. The wheels have just started slipping and so are free to spin. The applied torque results in an instantaneous rotational acceleration of the whole...
  8. Ng2020

    Continuing Education and Certifications for Young Aero Designer

    It's good that they (presumably a smaller company) are interested in your continued development. Also have a look at the offerings from Kansas University. e.g Their 1309 course may be relevant to your employer's line of business and is an important subject area that not necessarily covered by...
  9. Ng2020

    HL12 hiloks

    I have been looking at hilok/hitigue usage across a number of different OEMs. Regarding the basic Ti hiloks HL10,11,& 12, , I noticed that while HL10 is called out by several OEMs in shear applications, its equivalent tension head, the HL12, is not in common usage for tension applications Is...
  10. Ng2020

    Torson moment in padeye with shackle

    Do a top view free body diagram. Does the applied force line of action pass through the shear centre (centroid for a rectangular section) of the red section?
  11. Ng2020

    Hi guys I am doing Project on Aeroe

    Do you mean that you are importing a BDF into Patran (or a similar pre/post processor)?
  12. Ng2020

    Unsymmetric Section Neural Axis Vs Principal Axes Maximum and Minimum Stresses

    https://newtonexcelbach.com/ has various section analysis tools implemented in excel. He is also a contributor on this forum.
  13. Ng2020

    Deutsch Blind Fasteners PN 6952-x-xx-x

    Is this getting close? At least there's a cage code and nsn which might provide some more leads. https://www.aerospaceunlimited.com/rfq/deutsch-fastener-corp/5320010063737/6952s06-4/
  14. Ng2020

    How can I self-learn finite element analysis in a group that does minimal FEM work?

    Greg, not as far fetched as you might think: we do have tests for dynamic seat structure in civil aero (2x.562), which can include representative support structure.
  15. Ng2020

    How can I self-learn finite element analysis in a group that does minimal FEM work?

    The FAA "generic issue paper" for FE validation is oft quoted in Safarian's various presentations. Even EASA have referenced it in proposed CM-S-14 Has anyone here ever seen it? I have looked high and low to no avail...
  16. Ng2020

    Steel mill terminology: "weld repair" - Do mills repair defects?

    Agree... it's a " no animals were harmed in the making of this film" kind of statement.
  17. Ng2020

    Fitting factor and casting factor

    Historically... See CAR3.303 "variability factors" ( = 'special factors' in today's parlance), which states the purpose of these factors is to ensure that the probability of a part being understrength is 'extremely remote'. I.e It's a probability argument, intended to maintain a desired level of...
  18. Ng2020

    Fitting factor and casting factor

    Careful- A fitting factor reflects uncertainty in the internal stress state (i.e. complex/uncertain internal loads) and may be removed if proof of strength for the detail is shown by test. You can find its origins in ANC-1, with some more flowery wording, from memory. Such uncertainty may...
  19. Ng2020

    Strain Gauging Instrumentation Help

    Fpr further reading try the AGARD flight test instrumentation report series.
  20. Ng2020

    Edge distance vs material thickness

    For a thick part with short edge margin, you could consider whether a lug analysis might be an appropriate means of characterising the static strength & durability for the detail. In terms of fatigue, considering the Kt for an open hole near an edge, I recall the variation stress concentration...

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